Water. desalination + reuse

TECHNOLOGY continuous operation. Amongst plant workers, the achievement of production targets and providing the associated benefits to the end user are generally one of the primary sources of job satisfaction. However, under Hot Standby, availability, and thereby security of water supply, is the goal rather than necessarily producing a given volume. GCDP staff in this way can be compared to a firefighting unit, in our case being called in the event of a watersupply emergency. Running in a minimum production mode means that in communicating and recognising staff efforts, the focus needs to change to reflect the paradigm shift from production to emergency supply . Keeping the asset in available and reliable condition is valuable to Seqwater and particularly those tasked with both the day to day and the long term water supply demand balance. Regarding staff capability, in highly complex process industries, starting a plant is the most difficult part of operation, providing the most potential for problems to occur prior to stabilisation of parameters and material stresses. These plants are typically operated continuously in a relatively stable manner, shutting down only when absolutely required. Therefore, Hot Standby presents an opportunity to develop a highly skilled operations team that has seen and solved many more issues than they otherwise would have under continuous operation. Figure 6: Remineralisation dosing stabilisation period Figure 7: Hot Standby supply history sitting in stainless steel pipework and fittings at the end of an operational cycle. The result being a higher risk of corrosion and the associated asset life and cost impacts. Based on expert advice, this risk is most effectively mitigated by flushing all steel surfaces with permeate on completion of an operational cycle. As a requirement of Hot Standby mode, automation of flushing facilities has been implemented. This automation ensures corrosion mitigation can be achieved without incurring ongoing unacceptable levels of manual operation. The automation also frees up operator time to carry out maintenance resulting in savings in contracted maintenance labour costs. STaff ExpErTiSE aNd CapabiLiTY Staff morale is another challenge created under Hot Standby mode relative to aCHiEvEmENTS Hot Standby mode has achieved savings in energy and chemical costs relative to continuous operation, all whilst keeping the desalination plant available to supplement water supplies due to preventative or breakdown maintenance or raw or potable water quality problems in other parts of the system. Since commencement of Hot Standby trials, the desalination plant has been used to mitigate supply risk either by the scheduling of maintenance at other plants to coincide with desalinated water production or in a limited number of cases by continuous operation of the plant. Most notably, during the 2013 Australia Day flood event, and as with the 2011 Brisbane flood event (see Figure 7), the water supply provided by the plant was one of the factors (along with the resilience of the system wide operational assets and staff ) that meant Brisbane was able narrowly to avert loss of supply in the most trying of circumstances. l August-September 2013 | Desalination & Water Reuse | 35 |

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